Due to recent advances in digital signal processing and communications technology, radio and TV broadcast signals are provided gradually in the form of digital data. As signals are provided in the form of digital data, a variety of information is now allowed to be added to TV or radio broadcast signals, the information including news, stock, weather, traffic, and so on.
In particular, necessity for traffic information is constantly increasing with the increment of the number of vehicles in downtown areas, the number of vehicles during holidays, and so on. Accordingly, methods for providing traffic information as auxiliary information via satellite, terrestrial broadcast, or mobile communications network are under development.